| A.N.T. Recordings Limited | London | 2016 |
| A.Naim Ltd | London | 2025 |
| A.P Scimeca Consulting Ltd | Bristol | 2024 |
| A.P Taylor Consulting Ltd | Guildford | 2015 |
| A.P. Charles Investments Ltd | Enfield | 1988 |
| A.P. Subcontracting Limited | Blackpool | 2011 |
| A.P.A. Computing Limited | Epping | 1988 |
| A.P.B. Communications Limited | Manchester | 1997 |
| A.P.Day Limited | Bristol | 2009 |
| A.P.G. Consultancy Limited | Uxbridge | 2004 |
| A.P.H. Computers Limited | Cheshire | 1984 |
| A.P.H. Services UK Limited | Wilmslow | 2001 |
| A.R IT Services Limited | West Midlands | 2007 |
| A.R. Mufti Limited | Teddington | 2014 |
| A.R.C. Music Acquisition Company I Ltd | London | 2021 |
| A.R.D Consulting Limited | Shepperton | 2014 |
| A.R.I Communications Limited | Widnes | 2018 |
| A.R.M Rigging Services Ltd | Houghton Le Spring | 2018 |
| A.R.M Technologies Limited | Bournemouth | 2023 |
| A.R.M. Setting OUT Limited | Shrewsbury | 2025 |
| A.R.M. Surveys Limited | Shrewsbury | 2013 |
| A.S Telecommunications Ltd | Reading | 2024 |
| A.S. Professional Ltd | Seaham | 2023 |
| A.S. Trilux Ltd | Swindon | 2015 |
| A.S.A. Services Limited | Essex | 1994 |
| A.S.C Cableing Ltd. | Waterlooville | 2013 |
| A.S.C. (Central) Limited | West Midlands | 1990 |
| A.S.K Digital Services Ltd | Woodley | 2017 |
| A.S.K. Partners Limited | London | 2016 |
| A.S.M Networks Ltd | Blackwood | 2018 |
| A.S.O. Business Solutions Ltd | London | 2016 |
| A.S.Radford Ltd | Harlow | 2013 |
| A.S.Rigging Ltd | Wiltshire | 2021 |
| A.S.T Comms Ltd | Middlesbrough | 2019 |
| A.S.T. Design Limited | Stourbridge | 2008 |
| A.Sadjid Project Services Limited | Newcastle Upon Tyne | 2016 |
| A.T. & G. Datanet Limited | Poole | 1991 |
| A.T. Oyston Limited | Kington | 2014 |
| A.T. Veterinary Systems Limited | Bury St. Edmunds | 1992 |
| A.T. Visuals Limited | Ashford | 2023 |
| A.T.A.N Industries Ltd | London | 2026 |
| A.T.E Services (Cheltenham) Limited | Cheltenham | 2007 |
| A.T.E. Data Limited | Edgware | 1988 |
| A.T.L Entertainment Ltd | Mitcham | 2019 |
| A.T.M. Limited | Thatcham | 1980 |
| A.T.Q. Soft Limited | Barnet | 2012 |
| A.Tabrizi Limited | Hythe | 2021 |
| A.U.U. Realisations Limited | Glasgow | 1985 |
| A.V.R. Group Limited | Altrincham | 1976 |
| A.V.T.V. Limited | Northampton | 1990 |
| A.W Projects & Programmes Ltd | Uckfield | 2023 |
| A.W Resources Ltd | Grays | 2017 |
| A.W. Golf Limited | Wimborne | 2014 |
| A.W.S . Group (N.I.) Ltd | Belfast | 2023 |
| A.Walia Ltd | Leicester | 2015 |
| A.Weddings Ltd | Birmingham | 2025 |
| A.X. Software Limited | Redditch | 2005 |
| A.Xodus C.I.C. | London | 2022 |
| A.Xodus Media Group Ltd | London | 2021 |
| A.Y Automation Limited | Smethwick | 2026 |
| A.You.K Limited | London | 2024 |
| A.Yusaf Limited | Manchester | 2021 |
| A.Zafirakou Limited | Kingsbury | 2018 |
| A/B Street Ltd | London | 2025 |
| A/Political LND Ltd | London | 2025 |
| A/Political Ltd | London | 2008 |
| A/V Revolution Ltd | London | 2011 |
| A1 Accounts Ltd | London | 2008 |
| A1 Aerospace Ltd | Belper | 2012 |
| A1 AI Ltd | London | 2025 |
| A1 Coaches Cleveland Limited | Cleveland | 2002 |
| A1 Compusolve Ltd | Bognor Regis | 2013 |
| A1 Consulting Services Ltd | Shirley, Solihull | 2022 |
| A1 Cyber Ltd | London | 2024 |
| A1 Data Analytics Ltd | London | 2020 |
| A1 Database Ltd | Slough | 2022 |
| A1 Datanetworks Ltd | Havant | 2011 |
| A1 DEV Solutions Ltd | Keighley | 2023 |
| A1 Dgtl Ltd | London | 2026 |
| A1 Digital Marketing Ltd | Lisburn | 2025 |
| A1 Document Solutions Ltd | Staffs | 2005 |
| A1 Enterprise Limited | Staines-Upon-Thames | 2024 |
| A1 Ergotech Limited | London | 2016 |
| A1 Information Technology Services Limited | Croydon | 2019 |
| A1 Installations (London) Limited | Sidcup | 2006 |
| A1 IT Consultancy Ltd | Stanmore | 2017 |
| A1 IT Limited | Liverpool | 2023 |
| A1 IT Networks Limited | Llanymynech | 2010 |
| A1 IT Services Ltd | Birmingham | 2025 |
| A1 IT Solutions Limited | Eastbourne | 2001 |
| A1 IT Systems Ltd | Barrow-In-Furness | 2009 |
| A1 Labels Limited | Beoley Redditch | 2002 |
| A1 Labs Limited | Farnham | 2025 |
| A1 Marketing Solutions Limited | Romford | 2019 |
| A1 Media Limited | London | 2012 |
| A1 Network Exchange Limited | London | 2021 |
| A1 Network Solutions Ltd | London | 2014 |
| A1 Networking Limited | Birmingham | 2022 |
| A1 North Internet Cafe Ltd | London | 2019 |
| A1 Overseas Consultancy Ltd | Hounslow | 2024 |